1. Field of the Invention
The present invention relates to a sealing device provided at the fuel supply port of a fuel tank for vehicles, such as automobiles.
2. Description of the Related Art
To prevent leakage of fuel vapor during refueling, a sealing device such as that shown in FIG. 5 is conventionally used. This sealing device includes a fuel supply port guide 4 and a shutter 8. The fuel supply port guide 4 has in its inner peripheral surface an annular groove 5, and a nozzle seal 1 is held in the annular groove 5. When a fuel supply nozzle 7 is inserted into the sealing device, the inner periphery of the nozzle seal 1 is brought into contact with the outer peripheral surface of the fuel supply nozzle, thereby preventing leakage of fuel vapor during refueling.
However, since the fuel supply nozzle 7 has various diameters and since there exists tolerance on the inner peripheral surface of the fuel supply port guide, in this conventional sealing device, the fuel supply nozzle 7 tends to be inserted in an eccentric fashion relative to the fuel supply port. This makes application of the face pressure of the nozzle seal 1 to the fuel supply nozzle 7 non-uniform in its circumferential direction, and thus deteriorates the sealing performance. Furthermore, when the eccentricity of the fuel supply nozzle 7 is great, it may be impossible for the nozzle seal 1 to follow the movement of the fuel supply nozzle 7, generating a gap between the nozzle seal 1 and the nozzle 7.